An essential element of leadscrew applications requiring close tolerance repeatability, is the elimination of backlash or "slop" between the fit of the follower nut and leadscrew. Historically, the method used to eliminate this lost motion or backlash has been to load one nut against another nut. This method works satisfactorily when the lead of the screw and nut is very consistent and lead accuracy is very high. However, the double nut method runs into difficulty when there are lead inaccuracies and inconsistencies in the leadscrew. Torque spikes and binding are caused by these inconsistent leads.
The increasing use of low cost, rolled thread leadscrews with their inherent lead inconsistency and inaccuracy has created a need for a follower nut able to operate smoothly on this and other similar types of leadscrews.
An additional need has been for a follower nut capable of adjustment due to wear of the screw and/or nut.